--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/bn_mp_grow.c	Mon May 31 18:25:22 2004 +0000
@@ -0,0 +1,51 @@
+/* LibTomMath, multiple-precision integer library -- Tom St Denis
+ *
+ * LibTomMath is a library that provides multiple-precision
+ * integer arithmetic as well as number theoretic functionality.
+ *
+ * The library was designed directly after the MPI library by
+ * Michael Fromberger but has been written from scratch with
+ * additional optimizations in place.
+ *
+ * The library is free for all purposes without any express
+ * guarantee it works.
+ *
+ * Tom St Denis, [email protected], http://math.libtomcrypt.org
+ */
+#include <tommath.h>
+
+/* grow as required */
+int mp_grow (mp_int * a, int size)
+{
+  int     i;
+  mp_digit *tmp;
+
+  /* if the alloc size is smaller alloc more ram */
+  if (a->alloc < size) {
+    /* ensure there are always at least MP_PREC digits extra on top */
+    size += (MP_PREC * 2) - (size % MP_PREC);
+
+    /* reallocate the array a->dp
+     *
+     * We store the return in a temporary variable
+     * in case the operation failed we don't want
+     * to overwrite the dp member of a.
+     */
+    tmp = OPT_CAST(mp_digit) XREALLOC (a->dp, sizeof (mp_digit) * size);
+    if (tmp == NULL) {
+      /* reallocation failed but "a" is still valid [can be freed] */
+      return MP_MEM;
+    }
+
+    /* reallocation succeeded so set a->dp */
+    a->dp = tmp;
+
+    /* zero excess digits */
+    i        = a->alloc;
+    a->alloc = size;
+    for (; i < a->alloc; i++) {
+      a->dp[i] = 0;
+    }
+  }
+  return MP_OKAY;
+}